This invention relates to a release mechanism for use with a hand held pneumatic valve operated device for requiring a positive action of the operator in order to release the valve operator to actuate a pneumatic device but which automatically returns to blocking position without further action by an operator.
Elongated pivoted handles extending in general longitudinal alignment with an elongated hand held housing containing the pneumatic power operated mechanism for operating tools are commonly used for actuating suitable control valves. It is an accepted practice to utilize pivoted blocking means which require the operator to disengage the blocking mechanism preparatory to actuation of the tool. Such a device is illustrated in U.S. Pat. No. 3,323,346. The operators sometimes neglect to return such operating mechanism to a blocking position so that such inadequacy of the safety feature subjects the tool to the inadvertent actuation as may occur as a result of improvidently depressing the operator mechanism.
Such hand held assemblies are often used for power crimping tools carried by the cylinders remote from the air inlet and because such tools are operated with great force by the multi-piston arrangements, inadvertent actuation thereof may be hazardous to the operator and others nearby. This hazard is increased by the necessity for utilizing a pivoted handle exposed along the outside of the cylinder. Firing of the multi-piston arrangement through actuation of the pivoted handle may occur inadvertently, for example, as a result of dropping of the tool by an operator.
Accordingly, it is desirable to provide a release mechanism for a pneumatic valve and a mechanism for operating same wherein it is necessary for the operator to manually release a blocking member which normally prevents inadvertent firing with a provision for automatically restoring the blocking mechanism to a position to block inadvertent actuation of the valve operator.